Large parent rolls are presently rolled up on a reel after a web manufacturing process such as during the production of tissue and other paper products. The parent rolls are prepared, stored and eventually transported to be converted and finished. To begin a converting process, the parent roll is unwound, subjected to a variety of conversions and re-wound into, for example, consumer-diameter size rolls called logs. A consumer-diameter size log is then transported to a packaging process where the log is cut into consumer-width size rolls and wrapped as finished product for shipment and subsequent purchase.
At least one drawback in the present state of the art is that parent rolls formed from uncreped through-air dried (UCTAD) tissue webs are prone to cause waste or lost production. The parent roll winding process can be wasteful due to the relative bulkiness of UCTAD tissue webs and the relatively large size of the parent rolls and loose winding tension vary throughout the parent roll. Additionally, thickness and width of the sheets of the parent roll undesirably varies due to different compressive stresses to the sheets in the parent roll at the top of the roll and approaching the core of the roll. The stretch in the sheet also varies in the parent roll due to the compressive forces (as mentioned above) and the wind-up process.
At least one other current disadvantage is that the web may not be completely supported throughout the manufacturing and winding processes. Intermittent support generally requires sheets to have increased tensile strength to pass over lengthy open draws. Also increased sheet tensile strength is necessary to overcome degradation due to winding and unwinding the parent roll before the converting process. However, due to higher web stresses on the sheets, the sheets tend to experience higher incidents of web breaks, which decreases machine efficiency. Such sheets also tend to cost more to manufacture. Higher costs, in turn, can be a competitive disadvantage since costs are likely passed on to the consumers in the form of higher retail prices, which may adversely impact consumer purchasing.
An additional disadvantage in the art is that tissue machine (TM) speeds presently tend to be faster than relatively slower converting process speeds. Accordingly, webs are not continuously moved from TM to the converting process. An intervening parent roll is usually required, which must be subsequently unwound and converted further reducing manufacturing and conversion efficiencies.
The present invention eliminates the parent roll and its associated reeling and unwinding steps by directly coupling a web-forming tissue machine to converting stations and a winder to make finished roll products. With the elimination of the parent roll and the inherent steps of winding and unwinding prior to converting, unwanted product waste and sheet thickness variability is reduced or eliminated. Additionally, elimination of the parent roll and extraneous winding and unwinding steps permits the web to be continuously moved from the forming step to the converting step, which increases overall manufacturing and finishing efficiencies.
According to an aspect of the invention, a method to transfer any type of sheet from, for example, a web drying system such as tissue, air-laid, non-woven (through-air dried, flat dryer or Yankee dryer) to the beginning of the winder is provided. The method utilizes a controlled sheet transfer from the drying system to the converting winder where a pulper or waste receptacle receives the sheet when the winder is not winding a consumer roll.
The method continuously supports the sheet from the drying or web-forming section to the winding section and allows for several sheet modifications, conversions or finishing steps such as calendering, embossing, s-wrapping (e.g., shear inducing reels to create shear forces that act upon the web to increase the softness of the web), coating, printing, web-separating, ply-bonding, and/or adhesive application prior to a winding or folding process. The sheet may be controlled via a belt, foil, fabric (permeable or non-permeable), air support, or vacuum support in various sections to allow the sheet to be processed through to wind-up without losing control of the sheet. Where small open draws may be required or desired, the method allows for broken web handling (xe2x80x9cbroke handlingxe2x80x9d) at each finishing or sheet modification station or at the end of the winding process.
According to another aspect of the invention, a web manufacturing system for directly forming and finishing the web product using the disclosed method is provided. The system includes a web-forming apparatus for forming and drying the web product and a conveyance system positioned downstream from a transfer point. The conveyance system continuously receives the web at the transfer point at a standard web processing speed while at least one converting station subsequently finishes the web. Although the system may include small open draws, for instance, to remove broken web, the invention contemplates substantially continuously controlling and supporting the web throughout the system.
Some benefits of the foregoing method and system are:
improved sheet properties (stretch and bulk or caliper are preserved with the elimination of the parent roll, reel and unwinding steps);
reduced capital costs due to fewer equipment pieces and no storage requirements for parent rolls;
reduced finished product variability (e.g., caliper variability in the parent roll sheet properties near the core and at the outside of the roll are eliminated or reduced);
reduced waste (e.g., no parent roll core, roll dressing thread-up on reel, or threading of the winder);
improved safety due to less equipment and handling of parent rolls;
improved climate/environment (e.g., no climate control required for parent rolls and a less dusty environment); and
increased web manufacturing and finishing efficiencies (e.g., no delay due to parent roll changes and no reel turn-up/thread-up delays).
The exemplary methods and the system described herein are simple, reliable, and economical to manufacture, assemble and use. Other advantages of the invention will be apparent from the following description and the attached drawings or can be learned through practice of the invention.